Polyamide-polyimide resin



United States Patent 3,522,270 POLYAMIDE-POLYIMIDE RESIN David W. Glaser, St. Paul, Minn., assignor to General Mills, Inc., a corporation of Delaware No Drawing. Filed Aug. 26, 1966, Ser. No. 575,261 Int. Cl. C07d 27/52; C09d 11/06 [S- Cl. 260-326 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the reaction product of an alkylene diamine, a polymeric fat acid, an anhydride acid, and certain monocarboxylic acids. The polyamidepolyimide resins thus formed are useful as flexographic ink binders.

This invention relates to novel polyamide-polyimide resins, their process of preparation and the use thereof as a fiexographic ink binder. In particular, the invention relates to polyamide-polyimide resins of an alkylene diamine, a polymeric fat acid, an anhydride acid, and certain monocarboxylic acids.

Resins suitable for use as ink binders in flexographic inks must provide a desirable combination of properties such as 1) low viscosity (2) good solution stability in isopropanol (3) good reducibility with isopropanol and denatured ethanol (4) good compatibility with nitrocellulose (5) good extensibility (6) good gloss (7) good adhesion to polyethylene and other polydiolefins after immersion in ice water, and

(8) low odor.

The polyamide-polyimide resins of this invention have been found to possess the combination of properties mentioned above when used in flexographic inks which are accordingly the primary area of use of the resins. The resins, however, may also find utility in lacquers and rotogravure inks.

As indicated earlier hereinabove, the particular polyamide-polyimide resins of this invention are those prepared by reacting under conventional amidification conditions, an alkylene diamine, a polymeric fat acid, an anhydride, and certain monocarboxylic acids.

In general, the resins are preferably prepared by reaction in the temperature range of 100-300 C. accompanied by removal of any by-product water. The reaction is preferably conducted in a two step temperature procedure by formation of the polyamide using the acids and diamine at a maintained temperature of about 140-460 C. for about A to 1 hour, followed by raising the temperature to about ZOO-250 C. and maintaining said temperature for a period of time of from 1 to 2 hours. The anhydride is preferably added at this point and the reaction continued at ZOO-250 C. for from 1 to 2 hours. The total time of reaction is not critical and it is merely required that the time be sufficiently long to provide a polyamidepolyimide resin. Usually the total time of reaction will be about 2 to 8 hours. Longer reaction times may be employed but generally are not necessary.

The alkylene diamines that are preferably employed are those of the formula where R is an alkylene radical having from 2 to 8 carbon atoms such as, ethylene diamine, diamino propane, diaminobutane, and hexamethylene diamine. R may be branched or straight chained, the straight chained radicals being more preferred.

Polymeric fat acids are commercially available products. A description of these acids and their method of preparation may be found in US. Pat. 3,201,471. As indicated in this patent, polymeric fat acids result from the polymerization of saturated, ethylenically unsaturated or acetylenically unsaturated naturally occurring or synthetic monocarboxylic aliphatic acids containing from 8 to 24 carbon atoms. Commercially the 18 carbon atom monocarboxylic acids such as oleic, linoleic, linolenic, and eleostearic acids are employed as starting materials for the preparation of the polymeric fat acids. Tall oil fatty acids which are predominantly a mixture of oleic and linoleic acids is the most common starting material.

After polymerization with or without a catalyst, the resulting product, is a mixture of predominantly dimeric fat acids, some trimeric and higher polymeric fat acids and some unpolymerized monomeric fat acids. Commercially available polymeric fat acids will have a dimeric fat acid content of about 60-80% by weight, a trimeric and higher polymeric fat acid content of about 10 to 35%, and a monomeric fat acid content of about 5 to 15% by weight. For the purposes of this invention, it is preferable that the dimeric fat acid content not exceed by weight and that the monomeric fat acid content not exceed 5% by weight.

Reference has been made above to the monomeric, dimeric, and trimeric fat acids present in the polymeric fat acids. The amounts of monomeric fat acids, often referred to as monomer (M), dimeric fat acids, often referred to as dimer (D), and trimeric or higher polymeric forms, often referred to as trimer (T), may be determined by the micromolecular distillation analytical method of R. F. Paschke et al., J. Am Oil Chem. Soc., XXXI (No. l), 5, (1954), wherein the distillation is carried out under high vacuum (below 5 microns) and the monomeric fraction is calculated from the weight of product distilling at up to C., the dimeric fraction calculated from that distilling from 155 to 250 C., and the trimeric (or higher) fraction based on the residue. Unless otherwise indicated, this analytical method was employed in the analysis of the polymeric fat acids employed in this invention;

The polymeric fat acids may be fractionated to provide products having higher dimer contents, by conventional distillation or solvent extraction techniques may be employed therefor. They may also be hydrogenated (before or after distillation) to reduce unsaturation, under hydrogen pressure in the presence of a hydrogenation catalyst. It is also understood that such other derivatives of polymeric fat acids which are capable of forming amides in reaction with a diamine, such as the lower alcohol (1-8 carbon atoms) esters of polymeric fat acids may be employed in place of the acids themselves in which the byproduct is then a lower alcohol rather than water.

The monocarboxylic acids to be employed in admixture to provide a polyamide-polyimide product having about equal and low amine and acid numbers (below 25 and preferably below 10). It is preferable that the amine equivalents be at least 90% of the carboxyl (including anhydride) equivalents employed. Expressed in ratio form,

. 5 with the polymeric fat acids are preferably isobutyric acid, the ratio of amine groups to carboxyl groups 18 prefer- 2-ethyl butyric, and 2-ethyl hexoic acid. These may be ably 0.9:1 to 1:1. used alone or a mixture thereof may be employed, mix- The amounts of reactants preferably employed may also tures thereof being most preferred. be expressed as follows:

The preferred anhydride to be employed is hexahydro- Reactant: Equivalent percent phthalic anhydride. With the combination of this an- Total carboxyl 100 hydride and the preferred monocarboxylic acids described (a) Polymeric fat acids 70 to 75 hereinabove, significant improvement or reduction in odor (b) Hexahydrophthalic anhydride 8 to results. Other anhydrides which may be employed in place c) Monocarboxyhc aclds 10 to 22 of the hexahydrophthalic anhydride are phthalic anhy- 15 Diamme 90 to 100 dfide, glutarleanhydl'idei de cenyl Succlmc enhydnde, The invention can best be illustrated by means of the decenyl succimc anhydrlde, 1tacon1c anhydrlde, and tetrafollowing examples in Which the resins were prepared by hyilmphthizhc d ll q il f t d t f the following procedure.

t is pre erre t at t e po ymeric a aci accoun or from 70 to 75 equivalent percent of the acid component RESIN PREPARATION p y including the anhydride The monocal'boxyllc The reactants, except the hexahydrophthalic anhydride acid (alone or mixture thereof) Preferably accounts P (see Table I for the reactants), are charged into a roundfIOm 10 to 22 equivalent P the remainder eqlllv' bottom 3-neck fiask fitted with a thermometer, mechanalenli Pefeent being furnished by the anhydride to 15 ical stirrer and distilling column and head. The mixture carboxyl equivalent percent). 25 is stirred and heated to 140 C. and held at this tempera- Where Special Properties are desired to Change some ture about 0.5 hour, at which point the by-product water properties such as S ft ning point and 211601101 Solubility, begins to distill off. The temperature is increased to about a c -m dify acid component may be p y in addi- 225 c. and held at this temperature for 2 hours, at which tion to the anhydride monoearboxylie acid described time the hexahydrophthalic anhydride in molten form is hereinabove- Where employed, Such eo-modifying acid added. The reaction is continued at about 225 C. for an component y be employed in an amount P to 25 q additional hour and then under vacuum for an hour at alent percent based on the total content of anhydride and 225 C, (Th anhydride is added at the indicated point monocarboxylic acid described above. Illustrative of such i th reaction s as to minimize the possible loss of the acids are lower aliphatic monoearboxylie acids Such as somewhat volatile and slow-reacting acids and to increase acetic and Propionie acids; Y Y monoearboXylie acid the formation of imide.) The vacuum is then released and such as lactic, glycolic, fi-hydroxypropionic, a-hydroxy-nthe product removed from the flask. o roio, fl-methylpropylhydracrylic acid, tetramethylhy- A varnish for a flexographic ink is prepared by dissolvdracrylic ac fi- Yd Y- y y Salicylic, p ing the polyamide resin as 35% non-volatiles in isoproylglycolic, and phenylacetic acids; relatively low molecpanol (99%). ular weight dicarboxylic acids such as succinic or phthalic Several resins employing hexahydrophthalic anhydride acid. and polymerized tall oil fatty acids were prepared by the Total carboxylic eqmvalents (derived from the polyabove-described method of preparation and evaluated for meric fat acid, monocarboxylic acid and acid anhydride) use as a flexographic ink binder. The reactants, amounts, are balanced with such a number of amine equivalents and evaluation can be seen from the following Table I.

TABLE I Example N0.

Composition-Equivalent Percent:

Polymericfatacid 73.0 73.7 73.7 72.8 73.2 73.5 74.7 73.8 74.3 71.8 71.9 Polymeric fat acid 71.3 71.7 72.0 72.0 Hexahydrophthalic anhydride 6.6 6.6 6.7 8.2 9.9 11.7 13.5 13.4 13.4 9.8 9.7 6.4 6.5 10.0 10.0 Isobutyric acid 10.2 7.0 6.8 12.0 10.7 9.4 5.5 8.1 8.0 10.4 10.4 7.9 10.0 10.0 2-ethylhexoic 3010-..- 10.2 12.3 10.4 8.0 11.9 13.9 8.0 8.0 2-ethy1 butyric acid--. 10.2 8.7 7.0 6.2 5.4 6.3 4.7 Suceinic anhydride..- 4.1 Ethylenediamine 08.4 90.3 97.3 97.0 95.5 93.7 97.5 93.3 93.6 95.7 95.7 93.0 98.0 96.5 96.5 Resin Properties:

Softening point B and R 0 105 103 102 109 102 105 99 103 94 103 105 102 101 103 106 Aminenumber 5.1 0.3 7.3 5.1 4.6 2.0 7.0 2.6 5.0 5.1 4.3 5.0 6.9 4.4 4.6 Acidnumben. 1.7 1.4 3.1 4.1 5.1 1.7 4.3 4.5 5.0 6.0 3.4 7.7 3.6 4.7 Properties as 35% N.V. 1n IPA Cplor-Gardner 8+ 11+ 10+ 8+ 8+ 8+ 8+ 8+ 8+ 7+ 8+ 9 7+ 7+ 7+ V1scos1ty-Gardner-H0ldt- B+ 13+ 0+ 13+ 13+ 13+ 13+ 0+ 0+ 13+ B+ B B B B Stability at 73 F.. days 34+ 27+ 27+ 27+ 49+ 51+ 27+ 51+ 51+ 38+ 35+ 30+ 30+ 24+ 24+ Gel Recovery at 40 F.,m1uutes 70 120 140 170 70 140 55 130 75 140 Reducibillty with IPA percent solids at hazepoint 1- 1 1- 1- Reducibility with Filmex A14 percent solids at N.C. Solids 40-80 Coating Properties:

Hardness-Sward 15 15 15 16 Extensibility .perceut-G.E Tack free time-minutes 3. 75 Bltoching F., 1 p.s.i., high humidity, face 0 2106 White Ink on Polyethylene 30% 30% Gloss,4rolls 73 70 68 70 73 60 72 67 71 71 69 70 68 65 Ice Crinkle test-l0=perfect. 2r0l1s. 6 2 2 2 2 2 8 4 8 4 4 4 4 6 6 1 Ty ical analysis: Percent M=1; M=79; Percent T=20; Acid Val.=l91; Sap. Val.=199. 2 Typical analysis: Percent M=3; Z, D=76; Percent T=2l; Acid Val.=l91; Sap. Val.=l99.

3 IPA=isopropanol 99+% grade.

4 Filmex Al=anl1ydrous denatured ethanol; SS=spirits soluble; NC=nitrocellulose;

6 Part.

Several resins employing anhydride other than hexahydrophthalic anhydride were prepared by the earlier described method of preparation. The compositions and results can be seen from the following Table II:

The embodiments of the present invention in which an exclusive property or privilege is claimed are defined as follows:

1. A polyamide-polyimide composition consisting es- TABLE II Example N o.

Composition, Eq. percent:

Polymeric fat acid 1 72 72 72 72 72 72 72 72 Phthalic anhydride 10 Glutaric anhydride Decenyl succinic anhydride Dodecenyl succinic anhydri e Itaconic anhydride Trimellitic anhydride Tetrahydrophthalic anhydride 2-Ethyl hexoic acid 8 8 8 8 8 Isobutyric acid 10 10 10 10 10 Ethylenediarm'ne 96. 5 96. 5 96. 5 93. 5 96.5 Resin Properties:

Softening point, B and R C 103 103 115 105 103 Amine number 5. 3 6. 4 2. 3 4. 0 5. 5 Acid number 4. 0 3. 1 3. 7 4. 0 3.0 3. 9 7. 0 4. 4 Properties as 35% N.V. in IPA:

Color-Gardner 8+ 8+ 6+ 6+ 7 12+ 13- 6+ Viscosity-Gardner-Holdt A A C C B Stability at 73 F., days 23+ 2 32+ 9 32+ 29+ 29+ Gel recovery at 40 F., minutes- 105 140 140 75 75 Reducibility with IPA percent solids at haze point Reducibility with Filmex A1 percent solids at haze porn Nistriiiclellulose compatability percent SS-l, N.C.

o s Coating Properties:

Hardness, Sward Extensibility, percent, G.E 60+ Tack free time, min Blocking 120 F., 1 p.s.i., high humidity-face to face. 65 White Ink on Polyethylene:

Gloss, 4 rolls 74 64 63 62 63 Ice Crinkle test, 2 rolls 6 2 4 9 9 6 2 0 1 Polymerized tall oil fatty acids, percent M=3; percent D =76; percent T=21. 2 Part. 3 None.

A typical ink formulation consists essentially of the resin as a binder, a solvent therefore and a pigment. Other optional ingredients are modifiers to provide optional characteristics. An ink formulation with the present resins will preferably be as follows:

(C) 8-15 equivalent percent of hexahydrophthalic Component: Amount, percent by weight Resin 20-30 24 carbon atoms, Solvent 5040 Pigment Ill-20 anhydride and Modifiers where employed will preferably be employed in an amount of about 3-7% by weight based on the total composition.

The solvents preferably are alcohols such as isopropanol or n-propanol. Water may also be present in relatively small amounts, up to about 10% by weight. Unsaturated alcohols such as methyl butynol may also be employed. Mixtures of solvents may also be employed such as a mixture of of isopropanol and isopropyl acetate. The alcohol solvents may also be blended with aliphatic hydrocarbons such as hexane or low boiling naphthas.

The pigments are conventional ink pigments, the particular pigment employed being dependent on the particular opacity, tinting strength, and color desired. Illustrative of some suitable pigments are rutile titanium dioxide, carbon black, iron oxide, chrome yellow, phthalocyanine blue, phthalocyanine green, chrome orange, molybdate orange, and toluidine red.

Illustrative of some suitable modifiers are certain rosin derivatives such as ester gums and modified ester gums, maleic resins, rosin maleic condensation products, phenolic resins, waxes and nitrocellulose.

A typical formulation for a fiexographic ink composition is as follows:

Parts by weight (D) 10-22 equivalent percent of a monocarboxylic acid, the improvement wherein said monocarboxylic acid is selected from the group consisting of isobutyric acid, 2- ethyl hexoic acid, Z-ethyl butyric acid and mixtures thereof.

2. A polyamide-polyimide composition as defined in claim 1 wherein said polymeric fat acid is polymerized tall oil fatty acids, said diamide is ethylene diamine and said mono-carboxylic acid is a mixture of isobutyric acid and 2-ethylhexoic acid.

3. A polyamide-polyimide composition as defined in claim 1 wherein said polymeric fat acid is polymerized tall oil fatty acids, said diamine is ethylene diamine and said monocarboxylic acid is a mixture of isobutyric acid and 2-ethyl butyric acid.

4. A polyamide-polyimide composition as defined in claim 1 wherein said polymeric fat acid is polymerized tall oil fatty acids, said diamine is ethylene diamine acid, said monocarboxylic acid is Z-ethyl hexoic acid.

References Cited UNITED STATES PATENTS 3,383,391 5/1968 Carlick et al 260326 ALEX MAZEL, Primary Examiner Resin of this invention 25 J. A. NARCAVAGE, Assistant Examiner Solvent (isopropanol-99% grade) 55 Pigment (rutile titanium dioxide) 15 Modifier (nitrocellulose) 5 106-27, 26; 26018, 33.4, 78, 281, 326.3

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 522, 270 Dated July 28 1970 Inventoflg) David W. Glaser It is certified that error appears in the above-identified patent and that said Letters Patent: are hereby corrected as shown below:

Column 4, Table I footnote 1 delete M", second occurrence, and insert D Column 5 line 54 delete "of", first occurrence Column 6, line 53, delete "diamide" and insert diamine Signed and sealed this 3rd day of November 1970.

(SEAL) Attest:

EDWARD M.FLETCI-IER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents FORM PO-IOSO 10-69) USCOMM-DC aoanmoo US. GOVIIIIIIINT PRINTING OFFICE 1 I! 0-in-3! 

